Last updated: March 2026
What Is Noughts and Crosses?
Noughts and Crosses, known as Tic Tac Toe in North America, is one of the oldest and most universally recognized strategy games in the world. The name comes from the marks used: noughts (O) and crosses (X). Archaeological evidence shows versions of this game carved into Roman roofing tiles from the first century BCE, and similar games appear in ancient Egyptian and Chinese artifacts.
Two players take turns placing their mark on a 3x3 grid. The first player to align three marks in a row, column, or diagonal wins the game. If all nine squares are filled without a winner, the game is a draw. While the rules are simple enough for a child to learn in minutes, the underlying strategy has made it a foundational example in computer science and game theory.
Our online version includes three AI difficulty levels and a 2-player mode. The Impossible AI is powered by the minimax algorithm and is mathematically unbeatable. Test your strategic thinking and see how consistently you can force a draw against perfect play.
How to Play Noughts and Crosses
Select a game mode from the options above the board. Easy AI makes random moves, Medium AI plays optimally about 70% of the time, and Impossible AI never makes a mistake. Two-player mode lets you play against a friend on the same device with customizable names.
Pick your mark by toggling between X and O. Crosses (X) always go first, giving a slight strategic advantage. If you choose Noughts (O), the AI will make the opening move. In 2-player mode, both players can enter their names for personalized score tracking.
Tap an empty cell to place your mark. Marks are drawn with smooth SVG animations. When three marks align, an animated line strikes through the winning cells and confetti celebrates the victory. The score tracker above the board keeps a running tally across games, and the collapsible Game History shows your recent results and win rates.
Frequently Asked Questions
What is the difference between Noughts and Crosses and Tic Tac Toe?
They are the same game. Noughts and Crosses is the traditional British and Australian name, while Tic Tac Toe is the American name. Noughts refers to the O marks and Crosses refers to the X marks. The rules, strategy, and gameplay are identical regardless of what you call it.
Can I beat the Impossible AI?
No. The Impossible AI uses the minimax algorithm to evaluate every possible future game state and always chooses the mathematically optimal move. The best you can achieve is a draw by playing perfectly. If you make even one suboptimal move, the AI will exploit it and win.
What is the minimax algorithm?
Minimax is a game theory algorithm that simulates every possible move for both players to the end of the game. It scores outcomes (+10 for AI win, -10 for human win, 0 for draw) and picks the move that maximizes the AI's minimum guaranteed score. This makes the AI unbeatable in Impossible mode.
Can I play Noughts and Crosses with a friend?
Yes. Select the 2 Players mode to play pass-and-play on the same device. You can set custom names for both players, and the score tracker keeps a running tally of wins, losses, and draws across multiple games.
Is Noughts and Crosses a solved game?
Yes. With optimal play from both sides, every game of Noughts and Crosses ends in a draw. There are 255,168 possible games but only 138 distinct final positions. The first player (X) can always force at least a draw, and the second player (O) can always prevent a loss with correct play.